The present invention relates to a water-tight endoscope comprising a flexible tube zone, a handle zone and a guide tube zone.
At the present, an endoscope which has been used for observation and clinical treatment in the colon is washed and disinfected and is then used again.
Accordingly, such an endoscope has an entirely water-tight structure so that at the washing step, washing water is not allowed to intrude into the interior of the endoscope.
In this water-tight endoscope comprising as constituent elements a flexible tube, a handle and a guide tube, these elements and connecting parts of these elements are completely sealed and the interior of the endoscope is sealed from the outer air.
In general, disinfection of an endoscope is carried out in an atmosphere of ethylene oxide gas (hereinafter referred to as "EOG") maintained at about 55.degree. C.
In the conventional water-tight endoscope having the above-mentioned structure, however, since the respective elements and the connecting parts thereof are completely sealed, the structure is not only water-tight but also airtight.
Therefore, if the conventional water-tight endoscope having the above mentioned structure is warmed to about 55.degree. C. at the disinfection treatment, the soft outer sheath of the flexible tube, especially an angle part, is swollen like a balloon.
Accordingly, swelling is repeated at every disinfection, resulting in the elastic fatigue, and a problem of reduction of the durability of the flexible tube is brought about by this elastic fatigue.
In the case where this swelling is extreme, the flexible tube bursts, and large-scaled repairing becomes necessary.